In this project, a comparison is carried out between the participating national measurement institutes in the field of humidity.
The aim of the comparison is to:
- Investigate the equivalence between the psychrometer calibrations performed by the participating laboratories.
- Gather practical calibration data and further information relevant for review of relative humidity CMCs.
- Gain practical experience for a similar but larger future comparison.
The method of comparison is calibration of a psychrometer in the range:
10%RH to 95%RH in the temperature range: 15 °C to 70 °C.
The 9 points to be measured are:
15 °C: 20%RH, 50%RH, 95%RH
45 °C: 10%RH, 50%RH, 95%RH
70 °C: 10%RH, 50%RH, 95%RH
Final Report 2011-03-22
Methods to realize a comparison of psychrometer calibrations were studied in this project. DANIAmet-DELTA benefitting its solid experience in psychrometry developed a Pt100-based psychrometer to be used as the transfer standard. Handling of the wick was found to be a major factor affecting the quality of the results.
As a final stage, a full comparison between the laboratories was carried out to study the equivalence of the psychrometer calibrations performed by the participating laboratories. As a summary of obtained results, degrees of equivalence divided by the associated expanded uncertainties (k=2) are given in the following table. The results were reported in details in Tempmeko & ISHM 2010 Conference [A. B. Kentved, M. Heinonen, D. Hudoklin, Practical study of psychrometer calibrations, submitted to Int. J. Thermophys.]